MICROSCOPIC DESCRIPTION: The cryobiopsy contains lung parenchyma with preserved architecture. There is mild interstitial thickening with scattered lymphocytes. Peribronchiolar accentuation of the interstitial changes is not obviously seen. Scattered multinucleated giant cells are present in the interstitium and they contain cholesterol clefts and calcified deposits. No granulomas are identified. There is no evidence of organising pneumonia. No eosinophilia is noted. The blood vessels show no evidence of vasculitis. No organisms are identified. The PAS stain shows no fungi. The Ziehl-Neelsen stain shows no acid fast bacilli. The Masson trichrome stain shows patchy mild interstitial fibrosis. There is no dense fibrosis or honeycombing. No evidence of malignancy is identified. In view of the clinical history, the overall features are most consistent with hypersensitivity pneumonitis. 

DIAGNOSIS: Right upper lobe cryobiopsy: Mild interstitial inflammation and fibrosis with giant cells, consistent with hypersensitivity pneumonitis.